Alarm bell and vibrator element therefor



July l0, 1951 F. w. JACKSON ET A1.

ALARM BELL AND VIBRATOR ELEMENT THEREFOR Filed Jan. 24A, 1949 Patented July 10, 1951 UNITED STATES PATENT OFFICE The invention relates generally to an alarm bell, and more particularly to a bell and vibrator structure therefor adapted to be operated on alternating current.

The invention has among its objects the production of a vibrator structure and bell assembly which is very simple in construction, relatively inexpensive to manufacture, and very elficient in operation, whereby a very loud alarm will be produced with relatively low voltages on the actuating winding and an attendant low current consumption.

Another object of the invention is the production of such a vibrator structure which employs only one moving part and which is so constructed that the alternating current Winding may be readily removed and replaced, whereby the same structure may be readily employed on diierent alternating current voltages by the substitution of a suitable winding.

Many other objects and advantages of the construction herein shown and described will be obvious to those skilled in the art from the disclosure herein given.

In the drawing, wherein like reference characters indicate like or corresponding parts;

Fig. 1 is a top plan view of a bell embodying the present invention, the covers being removed therefrom and part of the housing being broken away to show the details of construction;

Fig. 2 is a sectional view taken approximately on the line 2 2 of Fig. l; and

Fig. 3 is a sectional view taken approximately on the line 3 3 of Fig. l.

Referring to the drawing, I indicates a hollow, generally cylindrical housing open at one end with the latter closed by a `cover member 2 secured to the housing I by screws 3 or the like.

Mounted on the bottom 4 of the housing I is a base member of non-magnetic material, such as bronze or other suitable material, indicated generally by the numeral 5, the latter having a pair of horizontally extending portions 6 each of which is provided with an elongated slot 'I through which extend mounting screws 8 threaded into the bottom 4 of the housing. The base member 5 is also provided with a pair of spaced transversely extending upright portions 9 and II, respectively. The upright 9 is formed with a bore I2 therein axially aligned with a bore I3 in the upright I I, in which is slidably carried an armature I4 of a ferro-magnetic material, the diameter of the latter' being slightly less than the diameter of the bore I2. Rigidly carried by 2 striker I5. of non-magnetic material, which extends through the bore I3 and is of slightly less diameter than that of the bore I3.

Mounted on the respective uprights 9 and II are a pair of sleeves I6 and Il, respectively, through which the armature I4 and striker I5 extend, the bores of the respective sleeves being of slightly larger diameter than the diameter of the armature and striker to provide clearance between the respective parts, and, as illustrated in Figs. 2 and 3, the sleeves are each provided with a radially extending slot, the sleeve IB being provided with the slot I8, and the sleeve Il being provided with the slot 2l. The sleeves I6 and I1 are illustrated in the present instance as secured to their respective uprights by screws 22 and '23.

Positioned between the uprights 9 and II is a U-shaped permanent magnet indicated generally by the numeral 24, the legs 25 and 26 of which are provided with bores 2'1 and 28, respectively, through which the respective sleeves I6 and I'I extend, the diameter of the bores 21 and 28 being of approximately the same size as the adjacent portions of the respective sleeves. Positioned between the legs of the magnet 24 and encircling the armature I4 is winding 29, the latter being wound on a suitable spool 3| of nonmagnetic material.

The inner end 32 of the armature I4 is spaced from the adjacent end Ila of the sleeve II to form an air gap therebetween, the armature being maintained in its normal position by a leaf spring 33 secured at one end to the upright 9 by the block 34 and screws 35, the free end of the spring being slotted as indicated at 35, whereby the spring may bear against the head 3'I formed on the adjacent end of the armature I4.

Positioned adjacent the closed end of the housing I and secured thereto by a bolt 4I is a bell member 42, the bolt 4I passing through a hole in the bell 42 and threaded into a block 43 mounted on the bottom 4 of the housing by screws 44. Rotation of the bell 42 relative to the housing l is prevented by pin 45 engaging both the bell and the block 43. The striker I5 extends through a hole 46 in the side wall of the housing I and is of a length to strike the bell 42 when the device is actuated.

In the construction illustrated, the housing I is provided with a second cover member 4l, also secured to the housing by screws 48. The cover 2 carries a suitable socket 49 cin-operable with a plug 5I mounted on the cover 4l with the ends 52 and 53 of the winding '29 being connected to terminals 49a and 49h of the socket 49, and makes connection with the corresponding terminals Ia, and 5Ib of the plug 5I. Thus by rem-oving the screws 48, the bell structure, including the socket 49, may be readily separated from the member 41 and plug 5I, thereby facilitating removal or replacement of the bell structure.

The device is adapted to be actuated by the application of an alternating current to the Winding 29. Prior to the application of alternating current to the winding, the elements of the device will be in the position illustrated in Figs. 1 and 2 with the spring 33 maintaining the armature I4 and striker I5 in the position illustrated. It will be apparent that, as the adjacent end 32 of the armature I4 and sleeve and end I'Ia, of the sleeve I1 are of opposite polarity as a result of the magnetic forces existing in the legs 25 and 21 of the permanent magnet 24, the armature I4 will be attracted to the end I'Ia of the sleeve, which `action is resisted by the spring S3. Upon the energization of the winding 253 by an alternating current, as for vexample from a sixty cycle power line, the winding will create a magnetic eld which is alternating in polarity, which eld will thus alternatively oppose and supplement the permanent field set up by the magnet 24. Such action will result in axial vibration or reciprocation of the armature i4 and striker I5, with the striker hitting the bell l2 at the end of each outward stroke, thereby ringing the saine. The ac tion of the striker I5 is, of course, very rapid and results in a large volume of sound being produced by the bell 42. The efficiency of a ybell constructed in accordance with the present invention is readily illustrated by the fact that such a bell may be actuated under normal operation on approximately ,20% less current than alarm bells heretofore employed. Likewise, a bell employing a winding intended for use on a twelve volt circuit will provide an audible alarm when operated down as low as four volts, and similarly a bell constructed for normal use-on one hundred and fifteen volts will provide an audible alarm with only forty volts applied te the winding. The `present invention is particularly intended for use as an alarm in iire alarm circuits, and it is, of course, particularly desirable that the operation of the device not be dependent on critical operating voltages, so that the length, and lthus the resistance of the circuit wire, will have relatively little eiect on the satisfactory operation of the bell within wide limits.

It will also be noted that the device may be readily operated on different voltages merely by substituting a dierent winding 29, the remaining elements of the device being employed in either case.

The slots I3 and 2l in the sleeves I6 and I'I are provided merely to eliminate the building up Vof large induced currents in the structure, which would tend to heat up the same.

It might be mentioned rthat tests of bells constructed in accordance with the present invention indicate that a six inch bell, constructed as herein. shown and described, is comparable in `audible volume with eight inch bells presentlyemother applications Where a simple and inexpen- 4 I sive, but very ecient vibrator structure is required.

Having thus described our invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of our invention; hence, we do not wish to be understood as limiting ourselves to the exact form, construction7 arrangement, and combination of parts herein shown and described, or uses mentioned.

What we claim as new and desire to secure by Letters Patent is:

1. In a bell structure, the combination of a housing, a base member of non-magnetic material positioned in said housing, a pair of spaced sleeve elements of ferro-magnetic material carried by said base member, said sleeves each having a bore therein axially aligned with one another, a U-shaped, permanent type magnet, each of the respective poles of the latter having a bore therein through which said sleeves respectively extend, an armature of ferro-magnetic material slidably carried in the bore of one of said sleeves with the inner end thereof positioned adjacent to but spaced from the other of said sleeves, said armature having an axially aligned extension of non-magnetic material at the inner end thereof positioned in the bore of the other sleeve, a eld winding positioned between the poles of said magnet and encircling said armature, said winding being adapted to be connected to a source of alternating current, a leaf spring mounted on said base member and engageable with said armature for restricting axial movement of the latter, and a bell member carried by said housing, a portion of which is positioned in the path oi an adapted to be struck by the extension of said armature.

2. In a vibrator structure, the combination of a base member of non-magnetic material, a pair of spaced sleeve elements of ferrounagnetic material carried by said base member, said sleeves each having a bore therein axially aligned with one another, a U-shaped, permanent type magnet, each of the respective poles of the latter having a bore therein through which said sleeves -respectively extend, an armature of ferro-magnetic material slidably carried in the bore of one of said sleeves with the inner end thereof positioned adjacent to but spaced from the other of said sleeves, Said armature having an axially aligned extension of non-magnetic material at the inner end thereof positioned in the bore of the other sleeve, a eld winding positioned between the poles of said magnet and encircling said armature, said winding being adapted to be connected to a source of alternating current, and a leaf spring mounted on said base member and engageable with said armature for restricting axial movement of the latter.

3. In a vibrator structure, the combination of a base member of non-magnetic material, a pair of spaced sleeve elements of ferro-magnetic material carried by said base member, said sleeves each having a bore therein axially aligned with one another and a radially extending slot rtherein extending from the periphery of the `respective sleeve to the bore therein, a U-shaped, 'permanent type magnet, each of the respective poles of the latter having a bore Atherein through which said sleeves respectively extend, an armature of vferro-magnetic material slidably carried in the bore of one of said sleeves with the inner end thereof positioned adjacenttobut spaced from the other of said `s1eev.es,said arma*- ture having an axially aligned extension of nonmagnetic material at the inner end thereof positioned in the bore of the other sleeve, a field winding positioned between the poles of said magnet and encircling said armature, said winding being adapted to be connected to a source of alternating current, and a leaf spring mounted on said base member and engageable with said armature for restricting axial movement of the latter.

4. In a bell structure, the combination of a housing, a base member positioned in said housing, a pair of spaced sleeve elements carried by said base member, said sleeves each having a bore therein axially aligned with one another, a U- shaped permanent type magnet, each of the respective poles of the latter having a bore therein through which said sleeves respectively extend, an armature slidably carried in the bore of one of said sleeves, said armature having an extension of non-magnetic material at one end thereof positioned in the bore of the other sleeve, a Winding inductively related to said armature, said winding being adapted to be connected to a source of alternating current, spring means related to said armature for restricting axial movement of the latter, and a bell member carried by said housing, a portion of which is positioned in the path of and adapted to be struck by the extension of said armature.

5. In a bell structure, the combination of a' housing, a base member positioned in said housing, a pair of spaced sleeve elements carried by said base member, said sleeves each having a bore therein axially aligned with one another, permanent magnet means related to the respective sleeves whereby the latter are of opposite polarity, an armature slidably carried in the bore of one of said sleeves, said armature having an extension of non-magnetic material at one end thereof positioned in the bore of the other sleeve, a winding inductively related to said armature, said winding being adapted to be connected to a source of alternating current, spring means re-I lated to said armature for restricting axial movement of the latter, and a bell member carried by said housing, a portion of which is positioned in the path of and adapted to be struck by the extension of said armature.

6. In a vibrator structure, the combination of a base member, a pair of spaced sleeve elements carried by said base member, said sleeves each having a bore therein axially aligned with one another, a U-shaped permanent type magnet each of the respective poles of the latter having a bore therein through which said sleeves respectively extend, an armature slidably carried in the bore of one of said sleeves, said armature having an extension of non-magnetic material at one end thereof positioned in the bore of the other sleeve, a winding inductively related to said armature, said Winding being adapted to be connected to a source of alternating current, and spring means related to said armature for restricting axial movement of the latter.

7. In a vibrator structure, the combination of a base member, a pair of spaced sleeve elements carried by said base member, said sleeves each having a bor-e therein axially aligned with one another, permanent magnet means related to the respective sleeves whereby the latter are of opposite polarity, an armature slidably carried in the bore of one of said sleeves, said armature having an extension of non-magnetic material at one end thereof positioned in the bore of the other sleeve, a winding inductively related to said armature, said winding being adapted to be connected to a source of alternating current, and spring means related to said armature for restricting axial movement of the latter.

8. In a vibrator structure comprising a permanent magnet formed by a pair of spaced, relatively xed, magnetically polarized members, said members being of opposite polarity, an elongated armature of permeable material operatively mounted with respect to one of said members and adapted to be inductively polarized thereby, said armature extending between said members, with one end positioned adjacent to, but spaced from the other member, means for supporting said armature for axial movement toward and away from said other member, a winding inductively coupled to said armature whereby the armature is adapted to be inductively polarized, said winding being adapted to be connected to a source of alternating current, and spring means related to said armature for restricting axial movement thereof.

9. In a vibrator structure comprising a permanent magnet, an elongated armature of permeable material, means for supporting said armature for axial movement, said permanent magnet including a pair of spaced, relatively fixed, magnetically polarized members aligned on the axis of said armature, the latter extending between said members, With one end of said armatures positioned adjacent to, but spaced from one of said pole members and movable toward and away from the same, a winding inductively coupled to said armature, said winding being adapted to be connected to a source of alternating current, and spring means operatively connected to said armature for restricting axial movement thereof.

FRANK W. JACKSON. HARRY M. NACEY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,048,913 Stuart et al Dec. 31, 1912 1,797,013 Moran Mar. 17, 1931 2,205,189 Edwards June 18, 1940 1,278,406 Serge Mar. 31, 1942 

